Quadrature modulator having phase shift and amplitude compensati

Details Quadrature modulator having phase shift and amplitude compensati Quadrature modulator having phase shift and amplitude compensati

1993-10-01

1994-11-22

Grimm, Siegfried H.

Modulators

Phase shift keying modulator or quadrature amplitude modulator

Including discrete semiconductor device

375 39, 375 52, 375 57, 375 67, H04L 2736

Patent

active

053672712

ABSTRACT:
A quadrature modulator includes a 0.degree./90.degree. phase shifter including only resistors, capacitors, and transistors that separates an input carrier wave into two carrier waves having a phase difference of 90.degree. from each other by differentiating and integrating. The quadrature modulator includes amplitude compensating circuits for converting the two carrier waves from sinusoidal waveforms to rectangular waveforms having predetermined amplitudes. The amplitude compensating circuits are inserted between the phase shifter and double-balanced mixers. The phase shifter consists of circuit elements appropriate for circuit integration and produces a high degree of orthogonality in its output signals as a function of variations in the characteristic values of the circuit elements. Complementary carriers having precise orthogonality as well as superior balance are input to double-balanced mixers. Accordingly, a superior modulation wave having fewer spurious components is obtained easily with simplified circuit integration.

REFERENCES:
patent: 5119399 (1992-06-01), Santos et al.
patent: 5293406 (1994-03-01), Suzuki
Yamamoto et al., "A 1.9 GHz-Band GaAs Direct-Quadrature Modulator IC With A Phase Shifter", GaAs IC Symposium, Oct. 1992, pp. 37-40.
Altes, "Monolithic RC All-Pass Networks With Constant-Phase-Difference Outputs", IEEE Transactions on Microwave Theory and Techniques, vol. MTT-34, No. 12, Dec. 1986, pp. 1533-1537.

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